Glycosylation of Therapeutic Proteins: Current Understanding of Structure–Function Relationships

A CMC Strategy Forum held in Washington, DC, on Sunday 28 January 2007 focused on two topics related to protein structure and function (1). First, analytical techniques used in the glycan analysis characterization included recent advances and correlations among the various tools. And second, current understanding of glycosylation’s functional relevance to therapeutic proteins was discussed in the context of its effects on biological activity, pharmacokinetics, and Fc effector functions (for monoclonal antibodies, MAbs). Progress has been made in the field of glycobiology since this forum took place, and those updates can be found in articles referenced herein.

Two Sessions
The morning session’s goal was to develop a general understanding of the variety of analytical tools available for carbohydrate analysis: their limitations, strengths, and suitability for use in routine lot-release monitoring. The plenary session was chaired by Rohin Mahtre (Biogen Idec) and Blair Fraser (FDA CDER), with three speakers:

• “Glycoprofiling Strategies to Support Production of Recombinant Therapeutic Proteins,” by Shekar Ganesa (Genzyme)
• “Future Trends in the Measurement of Biopharmaceutical Glycosylation,” by Daryl Fernandes (Ludger Ltd.)
• “Human Glycoforms Produced by GlycoFi Engineered Yeast Strains,” by Andy Standheim (GlycoFi).

Workshop questions addressed general capabilities and limitations of key analytical tools for glycan characterization; general approaches to characterizing glycoproteins (monosaccharide analysis, glycan profiling and identification, site occupancy); key factors differentiating characterization techniques from those used for routine lot release; and expectations for in-process and process-analytical technology (PAT) applications.

The afternoon session’s goal was to discuss regulators’ and industry’s current understanding of the structure–function relationship for glycosylated therapeutic proteins and develop a decision matrix to determine the relevance of glycosylation on biologic properties (potency, clearance, immunogenicity) of a given therapeutic. This session was chaired by Wassim Nashabeh (Genentech) and Blair Fraser (FDA CDER), with three speakers:

• “Biological Relevance of Glycosylation of MAbs,” by Jun Park (FDA)
• “Approach Towards Glycoform Diversity,” by Kurt Brorson (FDA)
• “Fc Carbohydrate and Clearance,” by Andrew JS Jones (Genentech, Inc.)

Workshop questions addressed primary considerations and supporting studies for assessing biological relevance of glycosylation for a given therapeutic; structure–function attributes; correlations between in vitro data and clinical observations; and primary considerations in providing appropriate glycan controls.

1 Siemiatkoski J, et al. Glycosylation of Therapeutic Proteins: Current Understanding of Structure–Function Relationships. BioProcess Int. 9(6) 2011: 48–53;

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